Daily Briefing: Tues. 6/21/2011

Summer officially begins at 1:16 p.m. today, marking the Northern Hemisphere's summer solstice, or the longest day of the year. (Technically, every day lasts about 24 hours, but the sun will be up longer today than usual.) Some 18,000 druids and pagans gathered at Stonehenge in England this morning to celebrate a millennia-old solstice festival, the Guardian reports, while other revelers from Russia to El Salvador honored the sun with their own celebrations. The solstice has even inspired a strange new [skipwords]Google doodle.[/skipwords]

So what's the big deal? Today may be the first day of summer, but as USA Today points out, it has felt like summer for weeks across much of the U.S. — residents of Laredo, Texas, for example, have already endured 33 straight days with temperatures of 100 degrees or higher. But the solstice doesn't necessarily mean the start of summer weather; it simply marks the astronomical beginning of summer, based on the sun's position relative to Earth. The sun will therefore be as high in the sky as possible today, and will linger above the horizon longer than any other day in 2011. And while global warming may be starting to help the planet warm up earlier in the year, it still takes several weeks after the solstice for summer to hit full swing. That's because [skipwords]oceans[/skipwords] are slower to heat up than land, and in mid-June they're still chilly from winter, helping cool the Earth's surface. It won't be until July or August that we're really feeling true summer heat.

While the summer solstice is a spiritual event for some and an astronomical side note for others, CleanTechnica points out the day also offers a good excuse to start "taking advantage of the sun." Zachary Shahan uses the occasion to highlight the growing benefits of solar power, arguing the solstice should remind us all of the giant power plant in the sky we so often take for granted. "On this summer solstice, while the Northern Hemisphere is bathing in sunshine more than any other time of the year," Shahan writes, "you might consider tapping into that clean energy source for some of your electricity or hot water needs."

Earth's oceans are in even more dire straits than previously thought, according to a new report being presented to the U.N. today. The seas are under siege from a grab bag of threats, the report's authors warn, including ocean acidification, rising water temperatures, melting sea ice, habitat destruction, water pollution and overfishing. These factors are bad enough on their own, but many of them are also combining to raise the specter of a "globally significant extinction event," according to the report.

"We now face losing marine species and entire marine ecosystems, such as coral reefs, within a single generation," write the 27 scientists who compiled the report. "Unless action is taken now, the consequences of our activities are at a high risk of causing, through the combined effects of climate change, over-exploitation, pollution and habitat loss, the next globally significant extinction event in the ocean." Earth has undergone five mass extinctions during the past 600 million years, including the most recent one 65 million years ago, which killed off the dinosaurs. With fish serving as the main protein source for a fifth of all humans — and with sea water helping to cycle oxygen and absorb carbon dioxide all over the planet — the idea of a marine mass extinction is "shocking," says Alex Rogers, scientific director for the U.N.'s International Program on the State of the Ocean.

Scientists have speculated for years that Earth might be in the midst of a sixth mass extinction, but the report's authors say the severity of the oceans' plight surprised even them. "It was a more dire report than any of us thought because we [normally] look at our own little issues," co-author Carl Lundin tells the AP. "When you put them all together, it's a pretty bleak situation." Some of the problems are daunting, namely those related to climate change, but the researchers emphasize that others, like overfishing, are relatively simple to solve. "Overfishing is now estimated to account for over 60 percent of the known local and global extinction of marine fishes," says co-author William Cheung. "Unlike climate change, it can be directly, immediately and effectively tackled by policy change."

As the world waffles over nuclear power in the wake of Japan's Fukushima Daiichi crisis, the AP reveals some unnerving news about atom-smashing in the U.S.: Radioactive tritium has leaked from three-quarters of all U.S. commercial nuclear power sites, and the problem appears to be getting worse. Both the frequency and severity of the leaks has escalated in recent years, the AP reports, even as federal regulators sustain the industry by extending the licenses of its reactors.

Tritium is a radioactive isotope of hydrogen, created as a byproduct of the atomic reactions that take place in nuclear reactors. As with all forms of ionizing radiation, "exposure to tritium increases the risk of developing cancer," the EPA warns. The isotope has leaked from at least 48 of 65 U.S. nuclear sites, according to a yearlong investigation by the AP into federal safety records, and leaks from 37 of those sites exceeded the federal drinking-water standard. In some cases, the AP reports, the leaks were hundreds of times over the limit. Most of the leaks were detected within the boundaries of the power plant, and while some did escape into the surrounding environment, none is known to have contaminated public water supplies. But tritium did seep into some residential drinking wells near reactor sites in Illinois and Minnesota, according to the AP, and in one case it leaked into an aquifer and a discharge canal that flows into New Jersey's Barnegat Bay.

While tritium is carcinogenic, the EPA also notes that, "because it emits very low energy radiation and leaves the body relatively quickly, for a given amount of activity ingested, tritium is one of the least dangerous radionuclides." Tony Pietrangelo of the Nuclear Energy Institute tells the AP the leaks pose no threat to public health. "The public health and safety impact of this is next to zero," he says. "This is a public confidence issue." But not everyone agrees, and some safety advocates worry the leaks may only hint at a broader issue. "Any leak is a problem because you have the leak itself — but it also says something about the piping," says Mario Bonaca, a former member of the federal Advisory Committee on Reactor Safeguards. "Evidently something has to be done."

The U.S. government has extended a ban on uranium mining in the Grand Canyon for another six months, the New York Times reports, although officials say they're still open to allowing such mining in the future. The decision keeps a million-acre buffer zone around the national landmark until 2012, and buys the government more time as it waits for the results of a study on how uranium mining could affect the area's natural environment.

Interior Secretary Ken Salazar explained in a press briefing Monday that expanded uranium mining around the Grand Canyon could threaten not only water supplies, but also air quality, local wildlife and pristine scenery. Such benefits could not be regained once lost, Salazar said, but he added that he's not ready to declare the canyon off-limits to all new mining claims over the next 20 years, as mining critics have requested. Salazar said his preferred solution would be to institute such a two-decade moratorium, a preference shared by many local and state officials as well as environmental advocates, but he argues that more scientific study is needed first. The small number of existing mining claims in the area will still be honored, but Salazar said he's leaning toward blocking any new mines around the canyon.

"This alternative, if ultimately selected," he said, "would ensure that all public lands adjacent to Grand Canyon National Park are protected from new hard-rock mining claims, all of which are in the watershed of the Grand Canyon." The moratorium was set to expire in July, but will now remain in effect at least through December. Salazar is expected to make a final decision after an environmental impact statement is completed later this year.

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